Air pumps for an engine exhaust gas cleaning system

ABSTRACT

An air pump constructed as a unit with a generator having a generator shaft, said air pump having a vane shaft integrally formed with the generator shaft and a rotor provided with an internal gear, said vane shaft being provided with a pinion meshing with said internal gear, whereby said rotor is rotated at a reduced speed as compared with the generator shaft.

United States Patent [19 1 Ishihara et a1.

[ AIR PUMPS FOR AN ENGINE EXHAUST GAS CLEANING SYSTEM [75] Inventors: Shinya Ishihara; Yoshihiro Suzuki,

both of Anjo, Japan [73] Assignee: Nippondenso Co., Ltd., Aichi-ken,

Japan [22] Filed: Oct. 20, 1972 [21] App]. No.: 299,450

30 Foreign Application Priority Data Nov. 1, 1971 Japan 46-101870 Nov. 9, 1971 Japan. 46-104460 [52} US. Cl 418/181, 418/138, 418/241 '[51] I Int. Cl. F0lc 13/00 [58] Field of Search 418/137, 138, 181, 241

[56] References Cited v UNITED STATES PATENTS: I

Cozette 418/241 June 25, 1974 1,987,882 1/1935 Watts...; 418/138 2,927,669 3/1960 Walerowski 418/181 3,132,632 5/1964 Kehl 418/138 3,373,929 3/1968 Partain 418/138 Primary ExaminerC. J. Husar t or e 48 firmlQ shmannDa kyrue Cushman 5 7] ABSTRACT An air pump constructed as a unit with a generator having a generator shaft, said air pump having a vane shaft integrally formed with the generator shaft and a rotor provided with an internal gear, said vane shaft being provided with a pinion meshing with said internal gear, whereby said rotor is rotated at a reduced speed as compared with the generator shaft.

5 Claims, Si-Drawing Figures 1. AIR PUMPS FOR AN ENGINE EXHAUST GAS CLEANING SYSTEM BACKGROUND OF THE INVENTION The present invention relates to an air pump for an engine exhaust gas cleaning system and more particularly to an air pump constructed as a unit with a generator.

Conventionally, it has been a common practice that an air pump of an engine exhaust gas cleaning system is driven separately from a generator by providing an additional power take-off pulley as in the case of a compressor for a cooling apparatus. However, in a modern automobile, it is necessary to mount in an engine room many accessories'required for solving pollution problems, so that it is not practical to have a separate driving system for the air pump. Particularly, in a small automobile which has little space, it is very difficult to provide a space for mounting such an air pump and a driving means therefor. v 1

Thus, it has already been proposed to make an air pump for an exhaust gas cleaning system as a unit with a generator to be driven through the same driving system. However, this manner of solution is subjected to a further problem in that a generator is generally operated with the maximum allowable speed of I3 ,000 rpm, while an air pump used for this purpose must be driven at a speed of 7,000 to,8,000 rpm or below. It may be a way to drive the generator at a lower speed comparable to that of the air pump, but the dimension of the generator must be undesirably increased when the driving speed is decreased. When the air pump is driven at a speed exceeding the maximum allowable limit, the

' rotating parts are excessively worn within a relatively short period, resulting in a reduced life of the pump..

SUMMARY OF THE INVENTION The present invention has as an object to eliminate the above disadvantages of conventional arrangements.

A further object of the present invention is to provide an air pump for an engine exhaust gas cleaning system, which is driven by the same shaft as a generator.

A further object of the present invention is to provide an air pump which is driven by the same shaft as but at a lower speed than a generator.

According to the present invention, the above objects can be achieved by providing, in an air pump constructed as a unit with a generator, gear means for transferring rotation of said generator to the rotor of the air pump with a reduced speed. Preferably, the gear means comprises a pinion gear secured to the shaft of said generator and an internal gear engaging with said pinion gear and secured to said rotor of the air pump. By suitably determining the gear ratio between the pinion gear and the internal gear, it is possible to drive both the generator and the air pump at optimum speeds.

The above and other objects and features of the present invention will become apparent from the following descriptions of the preferred embodiments taking reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of a conventional arrangement of a generator and an air pump;

FIG. 2 is a fragmentary sectional view of the generator-air pump unit shown in FIG. 1;

FIG. 3 is a cross-sectional view of the air' pump shown in FIG. 1;

FIG. 4 is a cross-sectional view of gear means employed in one embodiment of the present invention;

FIG. 5 is a fragmentary sectional view similar to FIG. 2 but showing an air pump employing the gear means shown in FIG. 4;

FIG. 6 is a cross-sectional view similar to FIG. 3 but showing the air pump shown in FIG. 5;

FIG. 7 is a fragmentary sectional view similar to FIGS. 2 and 5 but showing another embodiment of the present invention;

FIG. 8 is a cross-sectional view similar to FIGS. 3 and 6 but showing the air pump shown in FIG. 7; and,

FIG.'9 is a perspective view of a pinion gear used in the arrangement shown in FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, particularly to FIGS. 1 through 3 which show an example of conventional arrangement. In FIG. 1, the reference numeral 1 designates a generator for an automobile, and 2 an air pump for an engine exhaust gas cleaning system which are in driving connection with a pulley 3 mounted at one end of the generator. The pulley 3 is in driving connection with a pulley (not shown) mounted on an engine crankshaft. Referring now to FIG. 2, the generator 1 has a shaft 4 journalled through a bearing 5 on the housing 6 thereof. The air pump 2 has a housing 7 and a rotor 8 disposed in the housing. The rotor 8 is splined at its shaft portion 8a to the shaft 4 of the generator and supported in the housing 7 by means of bearings 9 and 10. The air pump 2 further has a vane shaft 11 secured to the end plate 7a of the housing 7. The shaft 11 rotatably supports vanes 12 through bearings 13.

In the above arrangement, the shaft 4 of the generator and the rotor 8 of the air pump 2 are rotated in the direction shown by an arrow A in FIG. 3 at the same speed, so that as far as the generator I is of a conventional size, the rotor 8 must be rotated at an excessive speed. Thus, the durability of the bearings 10 and 13 is adversely affected because the lubricating oil in the bearing is exhausted and the relative speed between the rotor 8, the vane 12 and the housing 7 is excessively increased.

The present invention is aimed to eliminate the above disadvantages and provide a structure which allows a generator to rotate at a relatively high speed while an air pump is rotated at a relatively low speed. According to the present invention, the air pump has a vane shaft integral with a generator shaft and rotated therewith at a relatively high speed. Said generator shaft has a pinion secured thereto and the air pump has a rotor provided with an internal gear meshing with said pinion on the generator shaft. The gear ratio of the pinion and the internal gear is so determined that the speed of the air pump rotor is reduced to two thirds to one half of the speed of the generator shaft.

Referring now to FIGS. 4 through 6, particularly to FIG. 5, the reference numeral 14 designates a housing both for a generator 1 and an air pump 2, and 15 a generator shaft joumalled by means of a bearing 5 on the housing 14. The generator shaft 15 has a pinion 18 secured to one end thereof. The air pump 2 has a rotor 19 having a stub shaft 16 formed with an internal gear 20. As shown in FIG. 4, the internal gear 20 is meshing with the pinion 18 on the shaft 15. The reference numeral 21 designates an end cover on which said rotor 19 is supported at its one end. The other end of the rotor 19 is supported through a bearing 23 on the housing 14. The reference numeral 12 designates vanes rotatably supported through bearings 13 on a vane shaft 17 which is integrally formed with the generator shaft 15.

In operation of the above arrangement, the vane shaft 17 is rotated at the same speed as the generator shaft 15 and, at the same time, the pinion 18 is rotated with the same speed. Thus, the internal gear 20 meshing with the pinion 18 is caused to rotate at a reduced speed. As the result, the rotor 19 of the air pump 2 is rotated at a reduced speed as compared with the generator shaft 15. It should be noted that, in this arrangement, the vane shaft 17 is rotated at the same speed as the generator shaft 15 while the rotor 19 is rotated at a reduced speed. Thus, the bearings 13 and 23 are not subjected to an overload due to an overspeed. As the rotor 19 rotates, the vanes 12 are also rotated about the vane shaft 17 which is offset from the rotating'axis of the rotor 19. Thus, the volume of the air chambers defined by the vanes 12, the rotor 19 and the housing 14 are cyclically changed and pump the air as shown by arrows B, C and D.

According to the above embodiment, although the generator 1 may be rotated at a relatively high speed, say 13,000 rpm, the speeds of the rotor 19 and the vanes 12 can be maintained to a relatively low value, for example, 7,000 to 8,000 rpm. Therefore, the bearing 23 of the rotor 19 can be free from excessive load. Further, the relative speed among the rotor 19, the vanes 12 and the housing 14 can be remarkably reduced. Since the vane shaft 17 is rotated at the same speed as the generator shaft in contrast to a stationary vane shaft in a conventional arrangement, the relative speed between the vanes 12 and the vane shaft 17 can be remarkably reduced. Therefore, it is possible to reduce the load on the bearings 13 for the vanes 12. Thus, the arrangement is particularly effective to increase the life of the air pump.

Referring further to FIGS. 7 through 9, there is shown a further embodiment of the present invention. In this embodiment, corresponding parts are designated by the same reference numerals as the previous embodiment. Referring to FIG. 7, the reference numeral 14 designates a housing both for a generator 1 and an air pump 2, and 15 a generator shaft supported through a bearing on the housing 14. At one end of the generator shaft 15, there is integrally formed a vane shaft 17. The generator shaft is further provided at said end with a pinion 18 which is in turn provided with a flange 18a integrally formed thereon at one side as shown in FIG. 9. The reference numeral 24 designates a collar which is mounted on the vane shaft 17 before the pinion 18 is secured to the vane shaft 17. The collar 24 is held between the pinion l8 and the shoulder portion formed on the vane shaft 17. The reference numeral l9 designates a rotor for the air pump having a stub shaft 16 provided with an internal gear 20. The internal gear 20 is in meshing engagement with the pinion 18 as in the previous embodiment. The reference numeral 21 designates a cover which supports one end of the rotor 19 through a bearing 22. The other end of the rotor 19 is supported on the housing 14 by a bearing 23. The numeral 12 designates vanes rotatably mounted on the vane shaft 17 through bearings 13. In this embodiment, the cover 21 is formed with a vent hole 21a and the rotor 19 is formed at one end with a hole 19b. Thus, the interior of the rotor 19 is in communication with the atmosphere. The housing 14 is provided at its outer surface with heat radiating fins 25 which are so positioned as to surround the gears 18 and 20.

In this embodiment, since the flange 18a and the collar 24 serve to shield the opposite sides of the pinion 18, the lubricant on the teeth of the interrneshing gear 20 and the pinion 18 is prevented from splashing out of the area of the gear mechanism. Thus, there is no possibility that the lubricant is exhausted from the gear mechanism, and the pinion 18 and the internal gear 20 operates without remarkable noise. Further, any heat produced by the meshing engagement of the pinion l8 and the internal gear 20 can be dissipated to the atmosphere through the heat radiating fms 25. The vent holes 19b and 21a provided in the rotor 19 and the end cover plate 21, respectively, serve to cool the interior of the rotor 19 by discharging heat in the rotor therethrough and also to maintain the interior of the rotor 19 substantially at the atmospheric pressure. It should further be noted that, by maintaining the atmospheric pressure in the rotor 19, it is also possible to prevent lubricant from being splashed out. If the pressure in the rotor 19 is above the atmospheric pressure, there may be produced a flow from the interior of the rotor through the space between the pinion 18 and the internal gear 20 and through the bearing 5 to the atmosphere accompanying the lubricant therewith. When one or both of the pinion and the internal gear is made of a plastic material, the gear noise will further be decreased.

Although the invention has thus been shown and described with reference to the preferred embodiments, it should be noted that the invention is in no way limited to the details of the illustrated arrangements, but many changes and modifications may be made without departing from the scope of the appended claims.

What is claimed is:

1. An air pump for cleaning exhaust gas from an internal combustion engine, being constructed in a unitary body together with a generator having a housing and a generator rotor shaft rotatably supported in the housing, said air pump comprising;

an air pump housing supported by and longitudinally extending from said generator housing,

a rotor rotatably mounted within said air pump housing, the rotating axis of said rotor being arranged in parallel and in eccentricity with said generator rotor shaft gear means for transferring the rotation of said generator rotor shaft to said rotor in a reduced rotational ratio, and

vane means rotatably supported-in said pump housing for being rotated co-axially with said generator rotor shaft by the rotational force of said rotor.

2. An air pump for cleaning exhaust gas from an internal combustion engine, said air pump being constructed in a unitary body together with a generator having a housing and a generator rotor shaft rotatably supported in said housing, said air pump comprising;

an air pump housing supported by and longitudinally extending from said generator housing,

a rotor rotatably mounted within said air pump housing, the rotating axis of said rotor being arranged in parallel and in eccentricity with said generator rotor shaft,

gear means for transferring the rotation of said generator rotor shaft to said rotor in a reduced rotational ratio,

a vane shaft extending from said armature shaft into said air pump housing, said vane shaft being an unitary portion of said generator rotor shaft,

gear means for driving said rotor by said generator rotor shaft in a reduced rotational ratio, and

a plurality of vanes rotatably supported on said vane shaft for being rotated by the rotational force of said rotor.

3. An air pump as in claim 2, wherein said gear means comprises,

a pinion gear fixedly mounted on said generator rotor shaft and an internal gear wheel fixed to said rotor for engaging with said pinion gear.

4. An air pump for cleaning exhaust gas from an internal combustion engine, said air pump being constructed in a unitary body together with a generator having a housing and a generator rotor shaft rotatably supported in said housing, said air pump comprising:

an air pump housing supported by and longitudinally extending from said generator housing.

a rotor rotatably mounted within said air pump housing, the rotating axis of said rotor being arranged in parallel and in eccentricity with said generator rotor shaft,

gear means for transferring the rotation of said generator rotor shaft to said rotor in'a reduced rotational ratio, said gear means including a pinion gear fixedly mounted on said generator rotor shaft and having a flange portion extending radially therefrom,

a collar positioned at the end of said pinion gear which is opposite to said flange portion and an internal gear wheel fixed to said rotor for engagement with said pinion gear, wherein said flange portion and said collar hold a lubricant between said pinion gear and said internal gear wheel,

a vane shaft extending from said armature shaft into said pump housing, said vane shaft being a unitary portion of said generator rotor shaft, and

a plurality of vanes rotatably supported on said vane shaft for being rotated by the rotational force of said rotor.

5. An air pump for cleaning exhaust gas from an internal combustion engine, said air pump being constructed in a unitary body together with a generator having a housing and a generator rotor shaft rotatably supported in said housing, said air pump comprising:

an air pump housing supported by and longitudinally extending from said generator housing;

a rotor rotatably mounted within said air pump housing, the rotating axis of said rotor being arranged in parallel and in eccentricity with said generator rotor shaft;

gear means for transferring the rotation of said generator rotor shaft to said rotor in a reduced rotational ratio, said gear means including a pinion gear fixedly mounted on said generator rotor shaft, and an internal gear wheel fixed to said rotor for engaging with said pinion gear;

a vane shaft extending from said armature shaft into said air pump housing, said vane shaft being a unitary portion of said generator rotor shaft, a plurality of vanes rotatably supported on said vane shaft for being rotated by the rotational force of said rotor; and

means for ventilating heated air in said housing.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIN Patent No. 3, 19,3 Dated June 25, 197A Inventor(s) Shinya ISHIHARA and Yoshihiro SUZUKI It is certified that: error appears in the above-identified patent and that: said Letters Patent; are hereby corrected as shown below:

2 An air pump for cleaning exhaust gas from an internal combustion engine, said air pump being constructed in a unitary body together with a generator having a housing and a generator rotor shaft rotatably supported in said housing, said air pump comprising: i

an air pump housing supported by and longitudinally extending from said generator housing,

a rotor rotatably mounted within said air pump housing, the rotating axis of said rotor being arranged in parallel and in eccentricity with said generator rotor shaft,

gear means for transferring the rotation of said generator rotor shaft to said rotor in a reduced. rotational ratio,

a vane shaft extending from said armature shaft into said air pump housing, said vane shaft being a unitary portion of said generator rotor shaft, and

a plurality of vanes rotatably supported. on said vane shaft for being rotated. by the rotational force of said rotor.

Signs and Brain] this thirtieth ay of Dwember1975 [SEAL] A ttes t:

RUTH C. MASON AME. DAWN Arresting Officer Commissioner of harms and Trademarks 

1. An air pump for cleaning exhaust gas from an internal combustion engine, being constructed in a unitary body together with a generator having a housing and a generator rotor shaft rotatably supported in the housing, said air pump comprising; an air pump housing supported by and longitudinally extending from said generator housing, a rotor rotatably mounted within said air pump housing, the rotating axis of said rotor being arranged in parallel and in eccentricity with said generator rotor shaft gear means for transferring the rotation of said generator rotor shaft to said rotor in a reduced rotational ratio, and vane means rotatably supported in said pump housing for being rotated co-axially with said generator rotor shaft by the rotational force of said rotor.
 2. An air pump for cleaning exhaust gas from an internal combustion engine, said air pump being constructed in a unitary body together with a generator having a housing and a generator rotor shaft rotatably supported in said housing, said air pump comprising; an air pump housing supported by and longitudinally extending from said generator housing, a rotor rotatably mounted within said air pump housing, the rotating axis of said rotor being arranged in parallel and in eccentricity with said generator rotor shaft, gear means for transferring the rotation of said generator rotor shaft to said rotor in a reduced rotational ratio, a vane shaft extending from said armature shaft into said air pump housing, said vane shaft being an unitary portion of said generator rotor shaft, gear means for driving said rotor by said generator rotor shaft in a reduced rotational ratio, and a plurality of vanes rotatably supported on said vane shaft for being rotated by the rotational force of said rotor.
 3. An air pump as in claim 2, wherein said gear means comprises, a pinion gear fixedly mounted on said generator rotor shaft and an internal gear wheel fixed to said rotor for engaging with said pinion gear.
 4. An air pump for cleaning exhaust gas from an internal combustion engine, said air pump being constructed in a unitary body together with a generator having a housing and a generator rotor shaft rotatably supported in said housing, said air pump comprising: an air pump housing supported by and longitudinally extending from said generator housing. a rotor rotatably mounted within said air pump housing, the rotating axis of said rotor being arranged in parallel and in eccentricity with said generator rotor shaft, gear means for transferring the rotation of said generator rotor shaft to said rotor in a reduced rotational ratio, said gear means including a pinion gear fixedly mounted on said generator rotor shaft and having a flange portion extending radially therefrom, a collar positioned at the end of said pinion gear which is opposite to said flange portion and an internal gear wheel fixed to said rotor for engagement with said pinion gear, wherein said flange portion and said collar hold a lubricant between said pinion gear and said internal gear wheel, a vane shaft extending from said armature shaft into said pump housing, said vane shaft being a unitary portion of said generator rotor shaft, and a plurality of vanes rotatably supported on said vane shaft for being rotated by the rotational force of said rotor.
 5. An air pump for cleaning exhaust gas from an internal combustion engine, said air pump being constructed in a unitary body together with a generator having a housing and a generator rotor shaft rotatably supported in said housing, said air pump comprising: an air pump housing supported by and longitudinally extending from said generator housing; a rotor rotatably mounted within said air pump housing, the rotating axis of said rotor being arranged in parallel and in eccentricity with said generator rotor shaft; gear means for transferring the rotation of said generator rotor shaft to said rotor in a reduced rotational ratio, said gear means including a pinion gear fixedly mounted on said generator rotor shaft, and an internal gear wheel fixed to said rotor for engaging with said pinion gear; a vane shaft extending from said armature shaft into said air pump housing, said vane shaft being a unitary portion of said generator rotor shaft, a plurality of vanes rotatably supported on said vane shaft for being rotated by the rotational force of said rotor; and means for ventilating heated air in said housing. 